Cosmic question mark

The Planck mission’s data put a kink in precision cosmology

STAR TRACK The Gaia spacecraft (illustrated above) is collecting data on position and motion for about 1 billion stars in the galaxy. The data may help resolve controversy over the pace of the universe’s expansion.

Milky Way: Serge Brunier/ESO; Gaia: D. Ducros /ESA

For as long as humans have wondered about it, the universe has concealed its vital statistics — its age, its weight, its size, its composition. By the opening of the 21st century, though, experts began trumpeting a new era of precision cosmology. No longer do cosmologists argue about whether the universe is 10 billion or 20 billion years old — it was born 13.8 billion years ago. Pie charts now depict a precise recipe for the different relative amounts of matter and energy in the cosmos. And astronomers recently reached agreement over just how fast the universe is growing, settling a controversy born back in 1929 when Edwin Hubble discovered that expansion.

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